"Today, I began a new chapter filled with hope," Manning said in a statement read by his long-time physician, Adam Feldman, MD, at a press conference Monday at Mass General. He thanked his doctors, and the donor, saying the procedure "quite literally saved my life."

"We're all extremely proud of this accomplishment, 3-1/2 years in the making," said Jay Austin, the hospital's chief of plastic and reconstructive surgery. "Our courageous patient, Thomas Manning, continues to do well and we are optimistic about his future."

Cetrulo told The New York Times that normal urination should be possible for Manning in a few weeks, with sexual function possible in weeks to months.

"He's doing well so far. He's up and about, out of bed," Cetrulo said at Monday's press conference. "So far, we're doing OK."

The world's first successful penis transplant was performed in South Africa in December 2014. That patient had his penis amputated three years earlier after complications from a circumcision performed in his late teens.

The university near Cape Town said in announcing the transplant in March 2015 that the 21-year-old patient, whose name was not released, made a full recovering following the nine-hour surgery and regained all function in the transplanted organ.

A man in China received a penis transplant in 2005. That operation also appeared to be successful, but doctors said the man asked them to remove his new penis two weeks later because of psychological problems experienced by him and his wife.